This invention generally relates to slider-operated flexible zippers for use in reclosable pouches, bags or other packages. In particular, the invention relates to gusseted reclosable packages having slider-operated zippers.
Reclosable fastener assemblies are useful for sealing thermoplastic pouches or bags. Such fastener assemblies often include a plastic zipper and a slider. Typically, the plastic zippers include a pair of interlockable fastener elements, or profiles, that form a closure. As the slider moves across the profiles, the profiles are opened or closed. The profiles in plastic zippers can take on various configurations, e.g. interlocking rib and groove elements having so-called male and female profiles, interlocking alternating hook-shaped closure members, etc.
Conventional slider-operated zipper assemblies typically comprise a plastic zipper having two interlocking profiles and a slider for opening and closing the zipper. In one type of slider-operated zipper assembly, the slider straddles the zipper and has a separating finger at one end that is inserted between the profiles to force them apart as the slider is moved along the zipper in an opening direction. The other end of the slider is sufficiently narrow to force the profiles into engagement and close the zipper when the slider is moved along the zipper in a closing direction.
Other types of slider-operated zipper assemblies avoid the use of a separating finger. For example, U.S. Pat. No. 5,809,621 discloses a slider-operated zipper assembly wherein one zipper profile has a pair of handles that cooperate with the slider. As the slider is moved in an opening direction, the handles are squeezed together to disengage the profiles. In U.S. Pat. No. 5,442,838, a slider-operated zipper assembly is disclosed wherein the zipper profiles are engaged and disengaged in the course of a “rolling action”. This “rolling action” is described as being achieved through cooperation between flanges on the profiles and shoulders which project inwardly from the arms of the slider. U.S. Pat. No. 6,047,450 discloses a zipper comprising a pair of mutually interlockable profiled structures. Portions of the two profiled structures form a fulcrum about which the profiled structures may be pivoted out of engagement when lower edges of the bases are forced towards each other
Gusseted bags having plastic zippers are well known in the reclosable packaging art. One advantage of such gusseted bags is that they may be opened more fully to facilitate filling the bag and later removing its contents. In some designs a gusseted side of the bag can be used to form a pouring spout by pulling the gusset outward and then inverting the bag, in which event the pourable contents of the package can be made to pour down the V-shaped channel formed by the gusset panels.
In early concepts for such bags, the profiles of the plastic zipper had to be sufficiently large to capture a double thickness of the bag film in order to accommodate the gussets when the package was closed. Later designs for gusseted bags have side gussets that include portions aligned with the interlocking zipper profiles that are relatively thin as compared with the remainder of the bag walls.
U.S. Pat. No. 6,325,543 discloses a gusseted bag in which zipper profiles on a carrier strip are attached inside the bag. Profile-free sections of the carrier strip form part of the gusseted sides in the region of the bag mouth. The gussets may be open at both ends of the bag to provide a spout at either end or may be sealed together at one end to provide a spout at the opposite end. The front and rear walls of the bag and the gussets are joined together by interlocking the profiles as well as by capturing the profile-free areas of the gussets between the interlocking profiles. U.S. Pat. No. 6,325,543 does not disclose operating the zipper by means of a slider.
U.S. Pat. No. 6,186,663 discloses an embodiment of a gusseted bag in which the zipper is operated by a slider. The slider is configured so that the gussets, when folded, do not interfere with the operation of the slider. Therefore the disclosed embodiment employs a slider that does not have a separating finger. When the zipper is closed by the slider, the upper sections of the gussets are folded and captured between the interlocked zipper profiles. End stops are provided on the outside of the zipper parts to prevent the slider from sliding off the ends of the zipper. At the end of the package where the slider is parked when the zipper is fully open, the gusset will always be folded. Consequently, the latter end of the package mouth can never be opened widely because the gusseted side of the package in the area of the zipper cannot be expanded. However, this provides “little or no interference with expansion of the package gussets, especially towards the bottom of the package”.
There is a need for alternative designs of gusseted bags having slider-operated zippers in which portions of the folded gussets are not captured between the zipper profiles, thereby allowing smooth uniform sliding of the slider along its entire run.